SWIP IWI system components SWIP Internal Wall Insulation provides a system based approach to internal wall insulation. The system has been tested and certified to demonstrate that all components work together as designed to deliver the required performance. The SWIP IWI System is designed for upgrading existing solid (or cavity) external walls. It consists of thermally engineered composite studs and insulation slabs, which can be combined to provide greater thicknesses of high-performance thermal insulation than achievable by using a single thickness. SWIP Studs are a composite of high performance extruded polystyrene insulation and Oriented Strand Board (OSB). Traditional internal wall insulation which uses traditional timber or metal studs leads to thermal bridging through the studs. This needs to be compensated for by increasing the thickness of the overall system. The innovative use of the thermally insulated SWIP Studs within the SWIP system prevents this and results in an overall thinner system.The SWIP IWI System has been designed to simplify the process of upgrading existing solid (and cavity) masonry walls whilst delivering high levels of thermal performance. Typical U-values.